Polyfunctional acrylate derivatives of caprolactone-polyols

Abstract

Described herein are polyfunctional acrylate derivatives of caprolactone-polyols. The derivatives have low viscosity, are thermally stable and impart toughness properties to radiation cured coatings utilizing them.

What is claimed is: 
     
       1. A process for the preparation of polyfunctional acrylate derivatives of caprolactone-polyols characterized by the structural formula: ##STR5## wherein R 1  is hydrogen or methyl, R 2  is the residue of a caprolactone-polyol, m is an integer of 2 to 6, and n is an integer of 0 to 2, with the proviso that m+n is greater than or equal to 3 and m is greater than n, comprising the steps of: (a) reacting acrylic acid or methacrylic acid with a caprolactone-polyol for a period of from about 3 to 8 hours at a temperature of from about 60° to 120° C. in the presence of from about 0.1 to about 5% by weight of a strong acid catalyst, and from 50 parts per million to about 2% by weight of a polymerization inhibitor for the acrylic or methacrylic acid, said reacting being conducted with simultaneous sparging of air or oxygen through the reaction mixture to produce a reaction product comprising said polyfunctional acrylate derivative;   (b) vacuum stripping said reaction product comprising said polyfunctional acrylate derivative, while sparging said air or oxygen therethrough; and   (c) recovering said polyfunctional acrylate derivative.   
     
     
       2. The process of claim 1, wherein said polyfunctional acrylate derivative is prepared by reacting acrylic acid with a caprolactone-polyol prepared from epsilon-caprolactone and trimethylolpropane. 
     
     
       3. The process of claim 1, wherein said polyfunctional acrylate derivative is prepared by reacting acrylic acid with a caprolactone-polyol prepared from epsilon-caprolactone and pentaerythritol. 
     
     
       4. The process of claim 3, wherein step (a) is carried out in the presence of a solvent which removes water formed during the reaction as an azeotrope. 
     
     
       5. The process of claim 4, further comprising the step of neutralizing residual acrylic or methacrylic acid present in the reaction product comprising said polyfunctional acrylate derivative prior to vacuum stripping.